The Wikipedia article for Lego Island mentions 'Most of these buildings are based on real Lego sets in circulation at the time of release for the game.' I haven't played the game in a long time but the 6350 Pizzeria set reminds me of the Pizzeria in-game.

The jail cell looks like something out of a set whilst the bridge and beach hut don't.

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While a few are indeed sets there are some I can't recall seeing (such as the Information Center, which was probably too specalised to deserve it's own set).

As already pointed out the Pizzeria set is very similar to the one in-game.

The set "6598 Metro PD Station" was the in-game police station, incuding jail. The helicopter could be build during in a minigame in the police station. Accessories like the box of donuts and flaming pizza were not included in the set.